Jodrell Bank Observatory - Transit Telescope

Transit Telescope

The Transit Telescope was a 218 ft (66 m) parabolic reflecting aerial built at Jodrell Bank in 1947. At the time, it was the largest radio telescope in the world. It consisted of a wire mesh suspended from a ring of 24 ft (7.3 m) scaffold poles, which focussed radio signals to a focal point 126 ft (38 m) above the ground. The telescope mainly looked directly upwards, but the direction of the beam could be changed by small amounts by tilting the mast to change the position of the focal point. The focal mast was originally going to be wood, but this was changed to a steel mast before construction was complete. The telescope was replaced by the fully steerable, 250 ft (76 m) Lovell Telescope, and the Mark II telescope was subsequently built on the same location.

The telescope was able to map a ± 15 degree strip around the zenith at 72 and 160 MHz, with a resolution at 160 MHz of 1 degree. It was used to discover radio noise from the Great Nebula in Andromeda—the first definite detection of an extragalactic radio source—and the remains of Tycho's Supernova in the radio frequency; at the time it had not been discovered by optical astronomy.